1. Field of the Invention
The present invention relates to a cutting tool for cutting a through slit in a tube, such as a plastic buffer tube used to enclose loose optical fibers or ribbons containing optical fibers in an optical fiber cable, thereby facilitating access to the optical fibers encased therein.
2. BACKGROUND AND OBJECTS OF THE INVENTION
Because of their high bandwidth capacity and small physical size, optical fibers are now used in a wide variety of telecommunication applications. However, optical fibers are fragile, and are also susceptible to stress and bending, which cause optical attenuation and decreased transmission efficiency. Consequently, mechanical protection of the fibers is necessary.
One conventional way to protect optical fibers is to surround a group of several fibers or ribbons containing optical fibers loosely within a buffer tube of a plastic material which can have a wall thickness of up to 2 mm. It is often necessary, however, to remove a portion of the tube and splice or otherwise join one or more of the individual optical fibers or ribbons disposed within a given buffer tube to other optical fibers or to various devices, It is therefore advantageous to provide a buffer tube cutting or slitting device which permits cutting and removal of a portion of the buffer tube, thereby facilitating access to the fibers or ribbons without also cutting or otherwise disturbing the optical fibers or ribbons within the buffer tube. It is further advantageous to provide a cutting device capable of accessing optical fibers not only at the end portions of the buffer tube but also at intermediate portions of the tube, such as required in a branch splicing operation, which is usually more difficult and potentially disruptive to an operating telecommunications system transmitting through the remaining optical fibers.
Illustrative of prior art tube cutting tools are U.S. Pat. Nos. 4,741,104 and 4,947,549 which describe hinged devices having two opposed but axially displaced blades. U.S. Pat. No. 4,972,581 describes a tool having a blade that shaves or planes layers off a buffer tube to expose the fibers therein. U.S. Pat. No. 5,050,302 discloses a complicated device for radially slitting cylindrical objects having blades activated by manually holding down a button for each blade and requiring the optical fiber to be pulled through the device at least twice and at a substantial angle from the axis of the tool, thereby greatly bending and stressing any delicate materials within the cylindrical object, such as optical fibers within a loose buffer tube.